Abstract This retrospective study reviews a series of teratomas of the neck and mediastinum aiming at defining the features of these particular locations. We recorded prenatal diagnosis, perinatal management, clinical and radiologic features, pathology, surgical strategies and results in cervical and mediastinal teratomas treated over the last 10 years. During this period we treated 66 children with teratoma of which 11 (6 male and 5 female) had cervicomediastinal locations. Five babies had cervical teratomas ex- tended into the anterior mediastinum in two cases. Prenatal diagnosis was made in three (two with polyhydramnios). Four babies were born by C-sec- tion and only one had a successful EXIT procedure. The diagnosis was confirmed by imaging and in- creased AFP. Surgical treatment involved total tumor removal and in one case subsequent removal of lymph node metastases. All children survived except one in whom airway could not be cleared at birth. Two children bear mild hypothyroidism. During the same period six patients aged 0–17 years were trea- ted for mediastinal teratoma. Only one was prena- tally diagnosed and only two had some dyspnea. Removal was performed either by median sternoto- my, thoracotomy, or thoracoscopy. They all survive and are free of disease. Teratomas of the neck may cause fetal disease and unmanageable neonatal air- way obstruction. Prenatal diagnosis and planned multidisciplinary management are mandatory at birth. In contrast, only some mediastinal tumors cause respiratory embarrassment. Although benign, these tumors are sometimes immature and may metastasize to regional lymph nodes. Total surgical removal is curative. Thyroid insufficiency may be present at birth in cervical teratomas and may be aggravated by surgery. Keywords Teratoma Æ Neck Æ Mediastinum Æ Newborn Æ EXIT Æ Thyroid Æ Thymus Introduction Teratomas are embryonal neoplasms that arise when totipotential germ cells escape the developmental control of primary organizers and give rise to more or less organoid masses in which tissues derived from all three blastodermic layers (ectoderm, endoderm, and mesoderm) can be identified. Their histologic features are therefore heterogenous and may include cystic or solid areas with organoid patterns as well as mature or immature components. These tumors are located more often in the sacrococcygeal region and in the ovary but they may be also found in many other anatomic re- gions. Sometimes they become symptomatic ‘‘in utero’’ threatening fetal survival or are detected by ultrasound screening. However, more often they are detected later during infancy and childhood because of symptoms that depend on their size and location. F. Martino Æ L. F. Avila Æ J. L. Encinas Æ A. L. Luis Æ P. Olivares Æ L. Lassaletta Æ J. A. Tovar (&) Department of Pediatric Surgery, Hospital Universitario ‘‘La Paz’’, Paseo de la Castellana, 261, 28046 Madrid, Spain e-mail: jatovar.hulp@salud.madrid.org M. Nistal Department of Pathology, Hospital Universitario ‘‘La Paz’’, Madrid, Spain Pediatr Surg Int (2006) 22:627–634 DOI 10.1007/s00383-006-1724-6 123 ORIGINAL ARTICLE Teratomas of the neck and mediastinum in children Francesca Martino Æ Luis F. Avila Æ Jose L. Encinas Æ Ana L. Luis Æ Pedro Olivares Æ Luis Lassaletta Æ Manuel Nistal Æ Juan A. Tovar Accepted: 12 June 2006 / Published online: 13 July 2006 Ó Springer-Verlag 2006